LIGAND-INDUCED MOVEMENT OF LYMPHOCYTE SURFACE MACROMOLECULES : IV. STIMULATION OF CELL MOTILITY BY ANTI-IG AND LACK OF RELATIONSHIP TO CAPPING

Microscopic examination of spleen lymphocytes discloses a small number moving at random at a given time. The majority of lymphocytes with this spontaneous movement are thymic derived. Addition of anti-Ig antibodies stimulates random movement of B lymphocytes. This movement depends upon a bivalent antibody and a metabolically active cell. The movement is inhibited by DFP, suggesting the involvement of a serine esterase. Also the anti-Ig stimulated movement of the lymphocyte is inhibited by cytochalasin B or by not allowing the cells to settle onto a surface. Lymphocytes treated with DFP or cytochalasin B, or untreated lymphocytes in suspension, capped the anti-Ig-Ig complexes. Hence, one can dissociate the surface capping of anti-Ig-Ig complexes from cell movement. We postulate that capping may result from superficial movements of the surface and/or from membrane flow, both of which are not related to actual translation of the cell on a surface. Four effects have now been observed following combination of a ligand with the antigen receptor on the B lymphocytes: redistribution on the surface of the complexes; pinocytosis and catabolism; shedding into the extracellular environment; and stimulation of translational movement.